A method for managing a thermal power rejected by one or more traction components in a thermal conditioning circuit of a vehicle with an electric powertrain

Abstract

There is described a method for determining a spill flow rate value (mT2B, mB2T ) in a thermal conditioning circuit ( TCC) with heat transfer liquid of t vehicle with an electric powertrain, wherein the thermal conditioning circuit ( TCC) includes a traction circuit (L_TRC), a cabin circuit (L_CAB), and a battery circuit (L_BAT ), the cabin circuit being connectable in fluid communication with the traction circuit by means of a first delivery branch and a first return branch, which are configured for the transit of a first spill flow rate (mT2C, mC2T ) coming from and returning to the traction circuit, the battery circuit being connectable in fluid communication with the traction circuit by means of a second delivery branch and a second return branch, which are configured for the transit of a second spill flow rate (mT2B,mB2T) coming from and returning to the traction circuit. Thanks to the method according to the invention it is possible to achieve an improved battery performance, which translates into an improved driving range in the long term and into a more reliable battery. Moreover, this leads to maximizing the exploitation of the thermal power rejected by the one or more traction components, by keeping the availability thereof even when its use is no longer needed, while meeting the targets and limitations related to the thermal conditioning, specifically to the heating, of the cabin and of the battery of the electric powertrain.

Description

[0001] " A method for managing a thermal power rejected by one or more traction components in a thermal conditioning circuit of a vehicle with an electric powertrain" ★ ★ ★ ★

[0002] TEXT OF THE DESCRIPTION

[0003] Field of the Invention

[0004] The present invention relates to thermal conditioning circuits of vehicles with an electric powertrain, specifically to circuits with heat transfer liquid. The invention was developed with particular reference to a thermal conditioning circuit with heat transfer liquid which operates in a heat exchange relationship with:

[0005] - one or more traction components, including for instance at least one electric traction motor, a corresponding inverter operatively associated therewith, and a corresponding transmission connecting the electric traction motor to at least one corresponding drive wheel, - a cabin of the vehicle, particularly for the heating thereof,

[0006] a battery of the powertrain of the vehicle, particularly configured to supply each electric traction motor of the powertrain (in the following, also denoted as "high-voltage battery")

[0007] and to the possibility of improving the energy efficiency thereof.

[0008] Prior Art

[0009] Referring to a thermal conditioning circuit of the type identified in the foregoing, the thermal power which is rejected by the one or more traction components and which is transferred to the heat transfer liquid circulating in the thermal conditioning circuit is generally reused for heating the high-voltage battery, since the heat transfer liquid which is in a heat exchange relationship with the high-voltage battery isthe same; however, when the rejected thermal power exceeds the heating needs of the high-voltage battery, said excess is simply rejected towards the external environment, particularly by dissipating it by means of the radiator. This leads to a loss of energy efficiency, since the thermal power rejected towards the external environment is no longer available for possible further uses when such a need arises. As a further consequence, when said need arises it is necessary to resort to one or more electric heaters ( for example, one upstream of a cabin heater, another one upstream of the high-voltage battery) in order to increase the temperature of the heat transfer liquid, with a further energy consumption. Such energy is electric energy which is drawn from the high-voltage battery, with a consequent reduction of the driving range of the vehicle.

[0010] Obj ect of the Invention

[0011] The invention aims at solving the technical problem outlined in the foregoing. Specifically, the object of the invention consists in maximizing the exploitation of the thermal power rejected by the one or more traction components, by keeping the availability thereof even when such thermal power is no longer needed, while also complying with the targets and the limitations of the thermal conditioning, particularly of the heating, of the cabin and of the battery of the electric powertrain. This is to be achieved in a thermal conditioning system which includes a single electric heater, specifically an electric heater comprised in a cabin circuit.

[0012] Summary of the Invention

[0013] The obj ect of the invention is achieved by means of a method having the features set forth in the claims that follow, which form an integral part of the technical disclosure provided herein in relation to the invention.

[0014] Brief Description of the FiguresThe invention will now be described with reference to the annexed Figures, which are provided by way of non-limiting example only and wherein:

[0015] - Figure 1 shows a thermal conditioning circuit wherein it is possible to implement the method according to the invention,

[0016] Figures 1A and ID show various circuit configurations which may be implemented in the circuit of Figure 1,

[0017] - Figure 2 is a general block diagram of the method according to the invention,

[0018] - Figures 3 to 6 and 10 to 12 are block diagrams showing various steps and / or deductions of the method according to the invention in a preferred embodiment thereof, and

[0019] - Figures 7 to 9 show time diagrams of some values of interest in the method according to the invention, obtained through simulations.

[0020] Detailed Description

[0021] As a general premise, the Figures annexed to the present description show a method according to the invention, with particular reference to a preferred embodiment, as well as a thermal conditioning circuit (Figure 1 ) wherein it is possible to implement the method according to the invention. However, this is to be construed as merely exemplary, since it is possible to envisage, as will be set forth in the following, the implementation of the method on other types of thermal conditioning circuits.

[0022] According to the invention, and with reference to Figure 1, there is defined a method for determining a spill flow rate value in a thermal conditioning circuit TCC with heat transfer liquid of a vehicle with an electric powertrain, wherein the thermal conditioning circuit TCC includes a traction circuit L_TRC, a cabincircuit L_CAB and a battery circuit L_BAT. The cabin circuit L_CAB is connectable in fluid communication with the traction circuit by means of a first delivery branch and a first return branch, which are configured for the transit of a first spill flow rate ('rhT2Cfor the first delivery branch, mC2Tfor the first return branch) coming from and returning to the traction circuit. The battery circuit L_BAT is connectable in fluid communication with the traction circuit by means of a second delivery branch and a second return branch, which are configured for the transit of a second spill flow rate (mT2Bfor the second delivery branch, 'rhB2Tfor the second return branch) coming from and returning to the traction circuit L_TRC. Moreover, the battery circuit L_BAT and the cabin circuit L_CAB are connectable in fluid communication with each other by means a third delivery branch and a third return branch, which are configured for the transit of a third spill flow rate exchanged between both circuits.

[0023] In more detail, referring to the diagram of the circuit TCC in the preferred implementation of the method according to the invention, the first delivery branch extends from a circuit node T2C / 1 (which is still part of the traction circuit L_TRC: it is a circuit node of insertion of the first delivery branch into the traction circuit) to a circuit node T2C / 2 (which is already part of the circuit L_CAB: it is a circuit node of insertion of the first delivery branch into the cabin circuit), whereas the first return branch extends from a valve VC2T (which is part of the cabin circuit L_CAB: it is a node of insertion of the first return branch into the cabin circuit) which delivers the first spill flow rate mC2T, to a circuit node C2T, which is again part of the traction circuit L_TRC (it is a node of insertion of the first return branch into the traction circuit L_TRC).

[0024] As regards the battery circuit L_BAT, the seconddelivery branch extends from a circuit node NT (which is still part of the traction circuit L_TRC) to a circuit node T2B (which is already part of the battery circuit L_BAT), whereas the second return branch extends from a second three-way valve VB2T (which is still part of the battery circuit L_BAT) which delivers the second spill flow rate mB2Tto a circuit node B2T (which is again part of the traction circuit L_TRC).

[0025] As regards the cabin circuit L_CAB, the third delivery branch extends from a third three-way valve C2B (which is still part of the cabin circuit L_CAB and which delivers a flow rate 'rhC2Btowards the battery circuit L_BAT) to a circuit node C2B (which is already part of the battery circuit L_BAT), whereas the third return branch extends from a fourth three-way valve VB2C (which is still part of the battery circuit L_BAT and which delivers a flow rate 'rhB2Ctowards the cabin circuit L_CAB) to a circuit node B2C (which is again part of the cabin circuit L_CAB).

[0026] Between the node T2C / 1 and the node C2T there is moreover arranged, in parallel with the traction circuit L_TRC, a radiator RAD which is configured to cool the heat transfer liquid leaving the one or more traction components TRC (thus, it is arranged downstream of the one or more traction components TRC in the first flow direction Fl ). The flow rate mT2R which enters the radiator RAD is regulated by means of a fifth three-way valve VT2R. The radiator RAD is arranged in parallel with the traction circuit along a circuit branch which extends from an inlet node (the node whereat the valve VT2R is located) to an outlet node R2T, wherein the inlet node and the outlet node are located between the insertion circuit node T2C / 1 of the first delivery branch on the traction circuit L_TRC and the insertion circuit node C2T of the first return branch on the tractioncircuit (L_TRC).

[0027] The valves VC2T, VB2T, VC2B and VB2C are controllable in such a way as to implement four circuit configurations, which are shown in the Figures 1A-1D. The following description indicates the variations with respect to the configuration of Figure 1, which has all circuits in mutual communication (which, at any rate, is a nonviable condition), and each of the Figures 1A-1D shows, for simplicity, only a few of the references of Figure 1. Each of the valves VC2T, VB2T, VC2B and VB2C generally comprises an operating condition wherein two ports out of three are always in fluid communication, in such a way as to ensure the circulation of heat transfer liquid in the respective circuit. The respective third port is made traversable in an amount proportional to the amount of the flow rates mB2Tand mC2T, and to the flow rate exchanged between the circuits L_CAB and L_BAT.

[0028] A first configuration corresponds to what is shown in Figure 1A, and envisages the interruption of the direct fluid communication between the traction circuit L_TRC and the battery circuit L_BAT, thus setting the flow rate mB2Tto zero. The valve VB2T operates to prevent the flow rate transit in the second delivery branch. Such a configuration corresponds to the case of a request for an active conditioning of the cabin and of the battery (i. e., a condition wherein the activation of the electric heater ECHc ) is requested, and of a request of mass flow rate of heat transfer liquid from the cabin circuit L_CAB to the traction circuit L_TRC which is greater than zero.

[0029] A second configuration corresponds to what is shown in Figure IB, and it envisages the interruption of the direct fluid communication between the traction circuit L_TRC and the cabin circuit L_CAB, thus setting the flow rate mC2T to zero. The valve VC2T operates to preventthe flow rate transit in the first return branch, thereby blocking the flow rate transit also along the first delivery branch. This configuration corresponds to the case of a request for an active heating of the battery in a condition wherein the electric heater ECHcab is powered, or wherein both the battery and the cabin request heating, but the mass flow rate requested by the cabin circuit to the traction circuit is equal to zero.

[0030] A third configuration corresponds to what is shown in Figure 1C, and it envisages the interruption of the direct fluid communication between the battery circuit L_BAT and the cabin circuit L_CAB, thus setting the flow rate exchanged between them to zero. The valves VB2C and VC2B operate to prevent the flow rate transit in the third delivery branch and in the third return branch. Such a configuration corresponds to the case of an absence of active heating of the battery instead of the cabin, and the mass flow rate requested by the cabin circuit to the traction circuit is greater than zero.

[0031] A fourth configuration corresponds to what is shown in Figure ID, and it envisages - in the same way as in Figure 1C - the interruption of the direct fluid communication between the battery circuit L_BAT and the cabin circuit L_CAB, thus setting the flow rate exchanged between them to zero; however, in addition, it envisages the interruption of the direct fluid communication between the traction circuit L_TRC and the cabin circuit L_CAB, thus setting the flow rate mT2Cto zero as in the configuration of Figure IB. The valves VB2C and VC2B operate to prevent the flow rate transit in the third delivery branch and in the third return branch, and the valve VC2T operates to prevent the flow rate transit in the first return branch, which blocks the flow rate transit also along the first delivery branch.

[0032] Said configuration corresponds to the case whereinboth the battery and the cabin are not to be heated actively, or wherein only the cabin requires an active heating, but the mass flow rate requested by the cabin circuit to the traction circuit is equal to zero. In such a configuration it is not possible to implement the method according to the invention, since the heat generated by the traction is sent indirectly (through the cabin circuit) to the battery circuit, without directly connecting both circuits (traction circuit and battery circuit). As anticipated in the foregoing, from an operational point of view it is impossible to have a configuration wherein all the circuits L_TRC, L_CAB and L_BAT are connected with one another.

[0033] Therefore, a heat recovery from the one or more traction components to the battery passes through the cabin circuit L_CAB only when there is a request for a combined heating of battery and cabin, and when the exchange of mass flow rate between the cabin circuit L_CAB and the traction circuit L_TRC is enabled.

[0034] Moreover, it should be noted that:

[0035] - the traction circuit extends between the node T2C / 1 and the node B2T, with the nodes NT, C2T, R2T and the node occupied by the valve VT2R being arranged between the node B2T and the node T2C / 1 in the order in which they are mentioned. The node B2T and the node T2C / 1 identify in particular a return branch of the traction circuit L_TRC, whereas a delivery branch is defined between the same nodes, but is located in parallel with respect to the return branch;

[0036] - the cabin circuit L-CAB develops between the nodes B2C, T2C / 2 and the node occupied by the valve VC2B, - the cabin circuit L_CAB develops between the node C2B, the node occupied by the valve VB2T, the node T2B and the node occupied by the valve VB2C.

[0037] Always referring to Figure 1, the traction circuit(L_TRC) includes:

[0038] - at least one traction component TRC (arranged along F_TRC) of said powertrain, traversed by a first flow rate of heat transfer liquid mTrcin a first flow direction Fl, wherein the at least one traction component TRC comprises an electric traction motor, an inverter operatively associated with the electric traction motor and a heat exchanger for a transmission lubricant of a transmission connecting each electric traction motor to one or more corresponding drive wheels of the vehicle, - a first circulation pump P_TRC1 (in turn arranged along F_TRC) having a delivery port arranged upstream of the at least one traction component TRC with respect to the first flow direction Fl of the heat transfer liquid, the first circulation pump TP supplying the first flow rate mTrcto the at least one traction component TRC. Preferably, the presence is envisaged of a further circulation pump P_TRC2 in the traction circuit L_TRC, arranged upstream of the node T2C1.

[0039] Referring to Figure 4, as will be further detailed in the following, and referring to the case of a vehicle with an electric powertrain and comprising at least one electric traction motor (Figure 4 shows the most general configuration possible, with one electric traction motor for each wheel of the vehicle), the at least one traction component TRC in the traction circuit L_TRC comprises, for each electric traction motor, at least one hydraulic series between the inverter (references INV1, INV2, INV3, INV4 ) operatively associated with the electric traction motor (references Ml, M2, M3, M4 ), the electric traction motor Ml, M2, M3, M4 itself, and a heat exchanger for a transmission lubricant (references WTOC1, WTOC2, WTOC3, WTOC4 ) of a transmission connecting the electric traction motor Ml, M2, M3, M4 to one or more corresponding drive wheels. With a greater numberof electric traction motors, as is the case of Figure 4, the at least one traction component comprises a plurality of hydraulic series connected in parallel with one another.

[0040] Referring again to Figure 1, the cabin circuit L_CAB comprises:

[0041] - a cabin heat exchange device CAB_HX configured to operate in a heat exchange relationship with a cabin air flow rate and traversed by a second flow rate

[0042]

[0043] of heat transfer liquid in a second flow direction F2, - an electric cabin heater ECHcab arranged upstream of the cabin heat exchange device (CAB_HX) with respect to the second flow direction F2,

[0044] and optionally, but preferably:

[0045] - a second circulation pump P_CAB having a delivery port arranged upstream of the electric cabin heater ECHcab with respect to the second flow direction F2 of the heat transfer liquid, wherein the second circulation pump P_CAB supplies the second flow rate mCabto the electric heater ECH and to the second heat exchange device CAB_HX.

[0046] Still referring to Figure 1, the battery circuit L_BAT includes:

[0047] - a battery heat exchange device BAT_HX configured to operate in a heat exchange relationship with a battery for supplying of one or more electric traction motors of the powertrain (or the high-voltage battery), wherein the battery heat exchange device BAT_HX is traversed by a third flow rate mBatof heat transfer liquid in a third flow direction F3,

[0048] and preferably:

[0049] - a chiller CHL for cooling the flow rate mBatof heat transfer liquid, arranged upstream of the heat exchange device BAT_HX with respect to the third flow direction F3,

[0050] and optionally, but preferably,- a third circulation pump P_BAT which supplies the third flow rate mBatto the battery heat exchange device BAT_HX.

[0051] There is no electric heater in the circuit L_BAT or in the circuit L_TRC.

[0052] Along the circuit TCC there are moreover arranged various temperature sensors, which are configured to detect the temperatures at the inlet and at the outlet of the components which are present in the circuit (such data are of interest in the method according to the invention), and specifically:

[0053] - a first temperature sensor TS1, configured to detect a temperature 7 of the heat transfer liquid at the inlet of the device BAT_HX,

[0054] - a second temperature sensor TS2, configured to detect a temperature T2of the heat transfer liquid at the inlet of the device BAT_HX,

[0055] - a third temperature sensor TS3, configured to detect a temperature T3of the heat transfer liquid at the outlet of the device BAT_HX,

[0056] - a fourth temperature sensor TS4, configured to detect a temperature T4of the heat transfer liquid at the outlet of the one or more traction components TRC, - a fifth temperature sensor TS5, configured to detect a temperature T5of the heat transfer liquid at the outlet of the radiator RAD,

[0057] - a sixth temperature sensor TS6, configured to detect a temperature T6of the heat transfer liquid upstream of the valve VC2T, thus substantially at the outlet of the device CAB_HX,

[0058] - a seventh temperature sensor TS7, configured to detect a temperature T7of the heat transfer liquid at the inlet of the one or more traction components TRC.

[0059] By means of calculations, there are moreover defined two virtual temperature sensors, specifically:a first virtual temperature sensor SR2T for estimating a temperature TR2TQof the heat transfer liquid in a position located between the nodes R2T (outlet node of the radiator RAD) and C2T (insertion node of the first return branch into the circuit L_TRC),

[0060] a second virtual temperature sensor ST2B for estimating a temperature TT2B. of the heat transfer liquid in a position located between the nodes C2T and NT.

[0061] The (virtual) temperature TR2TOis calculated downstream of the node R2T by writing the law of mixing (continuity equation) at the node R2T itself:

[0062] ™T2RTgt■ T5+ (mTrCTgt- mC2Trgt- mT2RTgt^ ■ T4

[0063] = (jnTrCTgt- mC2TTgt) ■ TR2TO

[0064] hence:

[0065] _ • T5+ (mTrCTgt- mC2Trgt- mT2RTgt^ ■ T4

[0066]

[0067] R2T° (m-Trcrgt ~ ™C2TTgt)

[0068] wherein:

[0069] T5and T4are, respectively, the temperatures detected by the sensors TS4 and TS5.

[0070] mTrc1y, mC2T1yL, mT2R1yLare, respectively, the target values of the (mass) flow rate in the traction circuit L_TRC, of the first spill flow rate, and of the flow rate at the inlet of the radiator RAD.

[0071] The (virtual) temperature TT2B. is calculated downstream of the node C2T by writing the law of mixing (continuity equation) at the node C2T itself, and as a function of the temperature TR2TO

[0072] 7ilc2TTgt■ T6+ (mTrCTgt- i^c2TTgt) ■ TR2TO= mTrCrgt■ TT2B.

[0073]

[0074] hence:"lc27T( / t‘ T6+ (mTrCTgtmC2TTgt) ■ TR2TQ

[0075]

[0076] wherein:

[0077] T6is the temperature detected by the sensor TS6. After having solved the calculation of the temperatures by the virtual sensors, it is possible to define the values (signals) of the second spill flow rate mB2Twhich are of interest for the method according to the invention.

[0078] This being said about the circuit TCC, the method according to the invention includes determining a target value riiB2TTgtof the second spill flow rate mT2B, mB2Tas a combination of a first value of the second spill flow rate IB2TFFdetermined by feedforward control, and a second value of the second spill flow rate ThB2TcLdetermined by closed-loop control, wherein determining the first value of the second spill flow rate ThB2TpFincludes:

[0079] - determining a sufficient value 'nT-B2TSllff of the second spill flow rate as a function of a target value of the third flow rate 'rhBatTgtof heat transfer liquid, as a function of a temperature T3of the third flow rate mBatat the outlet of the battery heat exchange device BAT_HX, as a function of a target value T2Tgtof a temperature of the third flow rate mBatof heat transfer liquid at an inlet of the battery heat exchange device BAT_HX, and as a function of a temperature TT2B. of the first flow rate mTrcof heat transfer liquid at an inlet of the second delivery branch (node NT, substantially coinciding with the node C2T as regards the temperature), - determining a maximum value of the second spill flow rate mB2T]Uas a function of a target value of the third flow rate ThBatTgtof heat transfer liquid, as a function of a temperature T3of the third flow rate mBatat the outlet of the battery heat exchange device BAT_HX, as a function of a maximum permissible value T2Maxof a temperature of the third flow rate mBatof heat transfer liquid at an inlet of the battery heat exchange device BAT_HX, and as a function of the temperature TT2B. of the first flow rate mTrcof heat transfer liquid at the inlet of the second delivery branch (node NT, substantially coinciding with the node C2T as regards temperature), - determining a reserve value of the second spill flow rate 'rhB2Teas a function of a maximum permissible value i-TrcMax he first flow rate mTrcof heat transfer liquid ṁTrcMaxis to be construed as the maximum permissible value of the flow rate mTrc, as a function of the needs of the one or more traction components), as a function of the temperature T3of the third flow rate mBatat the outlet of the battery heat exchange device BAT HX, as a function of a minimum permissible value T7 n,. of the temperature of the first flow rate mTrcof heat transfer liquid at an inlet of the at least one traction component TRC, and as a function of the temperature T3of the third flow rate mBatof heat transfer liquid at the outlet of the battery heat exchange device BAT_HX, wherein the minimum permissible value T7n,. of the temperature of the first flow rate mTrcof heat transfer liquid at an inlet of the at least one traction component TRC is a function of a minimum permissible value T4of the temperature of the first flow rate mTrcof heat transfer liquid at an outlet of the at least one traction component TRC, and wherein the minimum permissible value T4Min°f the temperature of the first flow rate mTrcof heat transfer liquid at the outlet of the at least one traction component TRC is a function of a target value (

[0080]

[0081] TlTgt+^Tpushcab 'SSebelow) of the temperature of the second flow rate mCabof heat transfer liquid at an inlet of the cabin heat exchange device CAB_HX,- determining the first value of the second spill flow rate in raw form (valueB2TFFF) as the greater of the sufficient value 'riiB2TSUff of the second spill flow rate and the lower of said reserve value of the second spill flow rate 'rhB2Teand said maximum value of the second spill flow rate THROT.. if there is an indication of the possibility of requesting the first spill flow rate ṁT2C,ṁC2Tby the cabin circuit L_CAB, or as the greater (22 ) between the sufficient value of the second spill flow rate fnB2TSUff and the maximum value of the second spill flow rate THROT.. if there is no indication of the possibility of requesting the first spill flow rate ṁT2C,ṁC2Tby the cabin circuit L_CAB. As regards the indication of the possibility of requesting the first spill flow rate ṁT2C,ṁC2Tby the cabin circuit L_CAB, it essentially corresponds to the possibility of exploiting the heat rejected by the one or more traction components for heating the heat transfer liquid in the cabin circuit L_CAB, based on a prediction of the possibility of using said heat during the mission, before the end thereof. If the spill flow rate mT2C, mC2Tis greater than zero, it is assumed that the heat is already being used, whereas if the flow rate at the beginning of the mission is zero, the prediction of a future use may anyway activate the possibility of heat recovery, which will be confirmed as soon as the flow rate acquires positive values;

[0082] - calculating the value of the second spill flow rate IB2TFFdetermined by feedforward control as the greater of a zero value and the lower of the target value of the third flow rate 'rhBatTgtof heat transfer liquid, the maximum value

[0083]

[0084] of the first flow rate mTrcof heat transfer liquid, and the value of the second spill flow rate in raw form (raw value) mR2Trr,

[0085] - calculating the second value of the second spill flow rate 'ri'iB2TCL determined by means of a closed-loopcontrol as a function of an error depending at least on the temperature T4of the first flow rate mTrcof heat transfer liquid at the outlet of the at least one traction component TRC, on the minimum permissible value T4Minof the temperature of the first flow rate mTrcof heat transfer liquid at the outlet of the at least one traction component TRC, on the temperature T2of the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX, on the maximum permissible value T2Maxof the temperature of the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX, and on the target value T2rgtof the temperature of the third flow rate rii-Bat of heat transfer liquid at the inlet of the battery heat exchange device BAT_HX.

[0086] All the steps of the method and the related deductions will be described in the following with reference to the Figures 2 to 12.

[0087] Referring to Figure 2, diagram 1, There is shown a general diagram of the method according to the invention, wherein it is possible to appreciate that the target value of the second spill flow rate is determined as the greater (block 2, MAX) of a zero value (block 4 ) and the lowest (block 6, MIN) of:

[0088] - a combination, specifically a sum (block 8 ) of the values mB2TpFand mB2TcL

[0089] - the target value mBatTgtof the third flow rate of heat transfer liquid mBat,

[0090] - a maximum value

[0091]

[0092] of the first flow rate of heat transfer liquid mTrc, and

[0093] - the maximum value of the second spill flow rate W-IUTMax ■

[0094]

[0095] As regards the values mB2Tsuff, mB2TMax, mB2TExtHton which the calculation of the value riiB2TpFis based, they can be defined as follows:i) 'rnB2TSUff is a value of the second spill flow rate which is sufficient to meet a target temperature value T2Tgtat the inlet of the battery heat exchange device BAT_HX,

[0096]

[0097] ii) is a maximum permissible value of the second spill flow rate, and specifically a value of the spill flow rate which leads to a maximum permissible temperature T2Maxat the inlet of the battery heat exchange device BAT_HX, specifically a temperature beyond which a thermal shock of the high-voltage battery would occur,

[0098] iii) mB2Tc, is a reserve value for the device BAT_HX, and specifically it is to be construed as a value of the second spill flow rate which in any case can be destined to the high-voltage battery (thus, to the device BAT_HX) even in the presence of a request for the first spill flow rate towards the cabin circuit L_CAB. In other words, it is a value of the second spill flow rate which in any case ensures a minimum temperature value T7Minat the inlet of the one or more traction components TRC, i. e. a minimum temperature value of the heat transfer liquid returning from the battery circuit L_BAT to the traction circuit L_TRC which, as a consequence, always ensures a target temperature value at the inlet of the heat exchange device CAB_HX.

[0099] The value 'riiB2TSUff may be determined by writing the equations of mixing at the nodes, and specifically the continuity equation at the node T2B:

[0100] ^B2TSuff‘ TT2Bi+ (mBatTgt- mB2Tsuff^ ■ T3= mBatTgt■ T2rgt

[0101] hence

[0102] _T2TgtT3^B2TSuff-t^b, _ ■ mBatTgt

[0103]

[0104] The expression uses the value T2rgtbased on the definition of ThB2Tsuff.

[0105] Similarly, always referring to the equations of mixing at the nodes, and specifically to the continuity equation at the node T2B, for the flow rate 'rhB2Tiliv / lICiX it is possible to write:

[0106] T. ~ T-3

[0107] mB2TMax~TmBatTgt

[0108] 1T2Bi13

[0109]

[0110] by simply replacing T2rgtwith T2Max.

[0111] On the other hand, always referring to the equations of mixing at the nodes, and specifically to the continuity equation at the node B2T, for the flow rate ^lB2Tc- it is possible to write:

[0112] ■ T2+ (ṁTrcMax- mB2TExtHt) ■ TT2B. = ṁTrcMax■ T? Min

[0113] hence:

[0114] _ TT2Bj ~ ^7MinmB2TExtHtrp rpmTrcMax

[0115]

[0116] 1T2Bi13

[0117] Again, it is possible to observe that the expression uses the value T7„. based on the definition of mB2Tc, As regards the temperature T7Min, it is connected to the temperatures T4of the heat transfer liquid at the outlet of the one or more traction components TRC, and 7 at the inlet of the cabin heat exchange device CAB_HX. Specifically, since the temperature T7Minis a minimum value of return of the second spill flow rate

[0118]

[0119] to the traction circuit L_TRC, the consequent temperature at the outlet of the at least one traction component TRC is a minimum value T4as well, and therefore it is a value sufficient to ensure a target temperature value 7at the inlet of the cabin heat exchange device CAB_HX, which corresponds to a target value sufficient to meet the request for thermal heating power of the device CAB_HX. The target temperature value 7 is defined as the sum ^Tgt+^TPUShCab! wherein T1Tgtis a nominal target value and TPushcabis a temperature reserve, specifically a positive increase, which is used as a calibration amount, thus a temperature reserve which enables, in the calibration phase, to minimize the electric power consumption by the heater ECHca.

[0120] Referring to Figure 3, diagram 10, the target temperature value T + TPushcab(block 12 ) is an input data item for determining the temperature T7Minby means of a stationary thermal calculation model ( 14 ) of the heat transfer liquid through the at least one traction component, thereby enabling to express T7Minas a function of T4M.n, obtaining the value of mB2TEx[Ht(block 16).

[0121] Referring to Figure 4, considering the most general configuration of electric powertrain, i. e. a four-motor configuration including four electric traction motors Ml, M2, M3, M4, each being operatively associated with a respective inverter INV1 (motor Ml ), INV2 (motor M2 ), INV3 (motor M3), INV4 (motor M4 ), and each being operatively associated with a respective heat exchanger for transmission lubricant WTOC1 (motor Ml ), WTOC2 (motor M2 ), WTOC3 (motor M3), WTOC4 (motor M4 ), wherein each heat exchanger receives and dissipates the thermal power rejected by the transmission lubricant by means of which the respective electric traction motor transmits the motion to the corresponding drive wheel. As can be seen schematically in Figure 4, for each electric traction motor the heat transfer liquid circulates in a hydraulic series of inverter - electric traction motor - heat exchanger for the transmission lubricant, in this order. Each series INV1-M1-WTOC1,INV2-M2-WTOC2, INV3-M3-WTOC3, INV4-M4-WTOC4 is hydraulically connected in parallel to the other series, so that the temperature of the heat transfer liquid at the inlet of the parallel arrangement of the hydraulic series is the temperature T7(thus, at the minimum value, T7Min), and the temperature of the heat transfer liquid at the outlet of the parallel arrangement of the hydraulic series is the temperature T4(thus, at the minimum value, T4).

[0122] Assuming the presence of stationary conditions, there is no increase of internal energy in each volume of heat transfer liquid, and thus the temperature of the heat transfer liquid between two subsequent components of each hydraulic series remains constant.

[0123] Such temperatures, which are all indicated in Figure 4, comprise:

[0124] TOutInv4: the temperature of the heat transfer liquid leaving the inverter INV1 ( leaving a cooling jacket thereof ), thus in a volume of heat transfer liquid located between the outlet of the inverter INV1 and the inlet of the motor Ml (of a cooling jacket thereof );

[0125] ToutMotl:the temperature of the heat transfer liquid leaving the motor Ml ( leaving a cooling jacket thereof ), i. e. in a volume of heat transfer liquid located between the outlet of the motor Ml and the inlet of the heat exchanger WTOC1;

[0126] ToutoiiExl‘ the temperature of the heat transfer liquid leaving the heat exchanger WTOC1, i. e. in a volume of heat transfer liquid located between the outlet of the heat exchanger WTOC1 and the outlet of the parallel arrangement of the hydraulic series;

[0127] TOut / ni?2: the temperature of the heat transfer liquid leaving the inverter INV2 ( leaving a cooling jacket thereof ), i. e. in a volume of heat transfer liquid located between the outlet of the inverter INV2 and theinlet of the motor M2 ( of a cooling jacket thereof ); ToutMot2:the temperature of the heat transfer liquid leaving the motor M2 ( leaving a cooling jacket thereof ), i. e. in a volume of heat transfer liquid located between the outlet of the motor M2 and the inlet of the heat exchanger WTOC2;

[0128] ^outoiiEX2:the temperature of the heat transfer liquid leaving the heat exchanger WTOC2, i. e. in a volume of heat transfer liquid located between the outlet of the heat exchanger WTOC 2 and the outlet of the parallel arrangement of the hydraulic series;

[0129] TOutInv3: the temperature of the heat transfer liquid leaving the inverter INV3 ( leaving a cooling jacket thereof ), i. e. in a volume of heat transfer liquid located between the outlet of the inverter INV3 and the inlet of the motor M3 ( of a cooling jacket thereof );

[0130] ToutMot3:the temperature of the heat transfer liquid leaving the motor M3 ( leaving a cooling jacket thereof ), i. e. in a volume of heat transfer liquid located between the outlet of the motor M3 and the inlet of the heat exchanger WTOC3;

[0131] ToutoiiEX3‘ the temperature of the heat transfer liquid leaving the heat exchanger WTOC3, i. e. in a volume of heat transfer liquid located between the outlet of the heat exchanger WTOC3 and the outlet of the parallel arrangement of the hydraulic series;

[0132] TOutInv4: the temperature of the heat transfer liquid leaving the inverter INV4 ( leaving a cooling jacket thereof ), i. e. in a volume of heat transfer liquid located between the outlet of the inverter INV4 and the inlet of the motor M4 ( of a cooling jacket thereof );

[0133] ToutMot4’ he temperature of the heat transfer liquid leaving the motor M4 ( leaving a cooling jacket thereof ), i. e. in a volume of heat transfer liquid located between the outlet of the motor M4 and the inlet of the heatexchanger WT0C4,

[0134] ToutoiiEX4‘ the temperature of the heat transfer liquid leaving the heat exchanger WT0C4, i. e. in a volume of heat transfer liquid located between the outlet of the heat exchanger WTOC4 and the outlet of the parallel arrangement of the hydraulic series.

[0135] As a consequence, the thermal evolution of the heat transfer liquid may be described as an increase, in stationary conditions, of the temperature of the heat transfer liquid from the inlet to the outlet of a traction component.

[0136] Generally speaking, it is possible to write, with respect to the model of the at least one traction component TRC and for each traction component, the general form of the Fourier equation

[0137] 1

[0138] p ' (Temp ~ 7 / n)—™Clnt ' ^Pcint ' (Tout Tin)

[0139]

[0140] th-Cmp wherein:

[0141] Rthis the thermal resistance between the component and the heat transfer liquid, which may estimated by means of experimental tests,

[0142] TCmpis the current temperature of the traction component (motor, inverter, transmission lubricant in the heat exchanger) measured by a corresponding sensor (or by a plurality of sensors),

[0143] TInis the temperature of the heat transfer liquid at the inlet of the traction component,

[0144] TOutis the temperature of the heat transfer liquid at the outlet of the traction component,

[0145] cPcint is the specific heat at constant pressure of the heat transfer liquid, calculated at an average temperature between the inlet and the outlet (of the traction component),ant is the mass flow rate of the heat transfer liquid through the traction component.

[0146] It is therefore possible to define a system of equations with reference to the thermal balance across each traction component in the circuit L_TRC, by considering, as flow direction Fl, the flow direction shown in Figure 4, and by moreover adding an equation of mixing at the outlet of the parallel arrangement of hydraulic series (the thirteen unknown values are highlighted by being underlined the first time that they appear in the system - and the first time only, thus the following occurrences of the same unknown values are not highlighted).

[0147] 1 / \ _ / (1) p ( TotlEx-L ~ ToutMotr) — WrCj ’Cpcint ' \^OutoitEx~thOilEx1' - ' ' - 1 / \ _ (2) p I I' / V / otj—lout / np I—^-Trc4Cpcint Toutinvi )

[0148] (3) ~ (TInV1— T7Min) = mTrCiCpcint ^Toutinv! ^7 Min) thlnv4(4) ' \ ToilEx2ToutMot2)—™Trc2■ r - I T — T Pclnt I ^u^0ilEx2 & UtMot2tfl0ilEx2' - ' (5) — \ TMot2— TOut1 — mTrC2Cpcint ^Out / np2thMot2 (6) „ (rInV2— T7Min} = mTrC2Cpcint ^^OutinV2Min^) thlnv2(7) — \ ToilEx3~ ToutMot3) ~ W-Trcs r Pclnt - I I T OutoilEx^ — T Outwot-z thoilEx3V-71 / \. (8) p (TMot3~Toutinv) - mTrC3Cpcint yToutMot^ ^OutinV3KihMot3V-17R ' (?Inv3 ^7Min) ~ ṁTrcs Cpcint \ToutinV3^Min thlnvz1 / \ _ (10) „ I ToilEx4. ~ ToutMot4] — ^-Trc4■ c Pclnt - I I T OutoilEx4— T OlltMOt4,tfl0ilEx4' ' (11) p ( lwot4—TOut1 — mTrCiCpcint \ ToutMOt4ToutinV4

[0149]

[0150] KihM0t4' - '1. 7 X (12) (I / 7IV4 TjMin) lilTrCj. Cpclnt \^0utinV4^^Min J thlnv4(13) mTrc■ T4Min= mTrC1■ ToutOUEX1+ ™-Trc3’ ^OutOUEX2+ ^-Trc3■ Tout0iiEX3+ ^TrCi ■ T0utOilEx4

[0151]

[0152] wherein: ṁTrC1, ṁTrC2, ṁTrC3, ṁTrC4are fixed fractions of the flow rate ṁTrcMax, and they correspond to the mass flow rate of heat transfer liquid flowing in each hydraulic series (the index 1, 2, 3, 4 is associated to the hydraulic series, and therefore - by way of example - ṁTrC1is the flow rate traversing the series INV1-M1-WTOC1).. cpClntis the specific heat at constant pressure of the heat transfer liquid, calculated at an average temperature between T4Minand T7Min, wherein T7Minis

[0153]

[0154]

[0155] the temperature T7Mincalculated at the previous step time, and initialized to the value T4Min. In other words,cPcint is preferably calculated by means of a map which uses, as input data item, a temperature T calculated as: T = (T4Min+ T7Min) / 2, wherein T7Minis initialized to the

[0156]

[0157] value T4Min.

[0158] Rth, Rth, Rthare - respectively - the thermal resistances of the i-th electric traction motor (Rth, i = 1, 2, 3, 4), of the i-th inverter (Rth, i = 1, 2, 3, 4), and of the i-th heat exchanger for the transmission lubricant (Rth, i = 1, 2, 3, 4).

[0159] By solving the system of thirteen equations ( 1 ) - ( 13) set forth in the foregoing, it is possible to express the temperature value T7Minas a function of

[0160]

[0161] T4.. It is therefore possible to calculate the value ṁB2Tso that the three values of the second spill flow rate m

[0162]

[0163] DRZ2-T‘ S<-uff ’ Max and mR2TEc.xtHt used for the feedforward control are known.

[0164] Referring to Figure 5, diagram 20, it schematically shows the calculation of the raw value ṁB2T

[0165] Fr,

[0166] F, which Rawdepends on the presence or the absence of an indication of the possibility of requesting the first spill flow rate ṁT2C,ṁC2Tby the cabin circuit L_CAB. Said indication of possibility is represented by a state variable CabRecoverypred, which acquires the logic state "0" (FALSE) when there is no indication of the possibility of requesting the first spill flow rate ṁT2C,ṁC2Tby the cabin circuit L_CAB, and the logic state "1" (TRUE) when there is an indication of the possibility of requesting the first spill flow rate ṁT2C,ṁC2Tby the cabin circuit L_CAB. The logic state of the variable CabRecoverypredis determined by control logics external to the method according to the invention, typically control logics pertaining to the management of the thermal conditioning of the vehicle cabin (they are generally predictive logics which detect the thermal state of all the thermal components of the vehicle throughout the duration of the mission, and which define whether it is convenient to use the heat rejected by the one or more traction components in order to reduce the energy consumption of the cabin heater ECHca or to increase the battery efficiency), but the general meaning of the variable CabRecoverypredresides in the priority of the cabin thermal conditioning (heating) targets over the battery thermal conditioning (heating) targets. In the diagram of Figure 5, this is exemplified by a switch SW20 (the variable CabRecoverypredwhereof defines the control variable C20) which outputs - and thus inputs into the block 22 - the value associated with the route " T" when CabRecoverypred= 1, whereas it outputs the value associated with the route F when CabRecoveryPred= 0.

[0167] In this regard, the value is determined as

[0168]

[0169] the greater (block 22, MAX) of the sufficient value ṁB2Tof the second spill flow rate and the lower (block 24, MIN) of the reserve value of the second spill flowrate ṁB2Tand the maximum value of the second spill flow rate ṁB2Tif there is an indication of the possibility of requesting the first spill flow rate ṁT2C, ṁC2Tby the cabin circuit L_CAB (CabRecoveryPred= 1), or as the greater between the sufficient value of the second spill flow rate ṁB2Tand the maximum value of the second spill flow rate ṁB2Tif there is no indication of the possibility of requesting the first spill flow rate mT2C, mC2Tby the cabin circuit L_CAB ( CabRecoverypred= 0).

[0170] In other words, if there is an indication of the possibility of requesting the first spill flow rate mT2C, mC2Tby the cabin circuit L_CAB in order to meet the needs of the cabin thermal conditioning (heating), then said request acquires priority, and the flow rater^lB2Tccis superiorly limited by the reserve value ‘‘‘‘Raw

[0171] ṁB2T(which is generally lower than ṁB2T), whereas the lower limit is ṁB2T, i. e. a value which at most is sufficient to meet the temperature target of the heat transfer liquid at the inlet of the device BAT_HX, but no more. On the contrary, if there is no indication of the possibility of requesting the first spill flow rate mT2c> TTT-C2T by the cabin circuit L_CAB ( CabRecoverypred= 0), all the spill flow rate may be directed towards the battery, with the upper limit being shifted upwards to the value 'rh ‘‘‘?■T‘ Mn,ax which ’, on a logical level, ' exceeds the minimum block 24.

[0172] Referring to Figure 6, diagram 30, it is therefore possible to calculate the value of the second spill flow rate ṁB2Tdetermined by feedforward control as the greater (block 32, MAX) between a zero value (block 34 ) and the lower (block 36, MIN) between the target value ṁBatof the third flow rate of heat transfer liquid ṁBat, a maximum value ṁTrcMaxof the first flow rate ṁTrcof heat transfer liquid, and the value ṁB2T. In other

[0173]

[0174] words, the value ṁB2Tis superiorly limited by the strictest of the values ṁBat,

[0175]

[0176] su. LTgt 'DB£2T1PPROW and mT‘r"C-MnAax', and inferiorly by the zero value, in such a way as to exclude the possibility of negative flow rate values.

[0177] The following Figures 7 to 9 show time diagrams related to the simulation of the evolution of a few values of interest for the feedforward control. Figure 7 comprises four diagrams 7A, 7B, 7C, 7D which are synchronized in time, wherein:

[0178] the diagram 7A shows the evolution of the temperatures T2, T2Max, T2rgt,

[0179] the diagram 7B shows the evolution of the temperatures T3, TT2B,

[0180] - the diagram 7C shows the evolution of the flow rates of the type ṁB2T, including ṁB2T, ṁB2T, ṁB2T- the diagram 7D shows the evolution of an electric power PwrECHconsumed to supply the heater ECHcab.

[0181] The results of the simulations as per the diagrams 7A-7D demonstrate that, as soon as the temperature TT2Bexceeds the temperature T3by a given threshold (instant t1, diagram 7B), the flow rate ṁB2Tacquires the highest possible value (ṁB2T) allowed for by the physical limitations (upper saturation, diagram 7C). When the current temperature of the heat transfer liquid at the inlet of the device BAT_HX (temperature T2, instant t2) reaches the target value T2, the power PwrECHabsorbed by the heater ECHCabdecreases (instant t3, diagram 7D) in the same way as ṁB2T, and the flow rate ṁB2Tdetermined by feedforward control keeps on following ṁB2T• As a consequence, in the case of battery heating only, the evolution of T2distinctly separates from T2Tgtand converges towards T2Max.

[0182] If only the cabin heating is requested, and CabRecoveryPred= 1, holds true, ṁB2Tis limited by the value of T7Min, which depends on the target temperatureat the inlet of the heat exchanger CAB_HX. In this scenario, the possible heat in excess rejected by the one or more traction components TRC, which is not necessary for the cabin heating, is absorbed by the battery, thereby improving the efficiency thereof.

[0183] Figure 8 comprises three diagrams 8A, 8B, 8C which are synchronized in time, wherein:

[0184] the diagram 8A shows the evolution of the temperatures T2, T2Max, T2rgt,

[0185] the diagram 8B shows the evolution of the temperatures T4, T4,

[0186] - the diagram 8C shows the evolution of the flow rates of the type ṁB2T, including ṁB2T, ṁB2T, ṁB2T.

[0187] From the simulations it is possible to observe that, as long there is no excess heat rejected by the one or more traction components TRC, T2follows the target value T2and the flow rate riiB2TpFdetermined by feedforward control remains equal to zero. Once the current temperature T4at the outlet of the one or more traction components TRC exceeds T4Minby a given threshold (instant t4), the flow rate ṁB2Tdetermined by feedforward control follows the evolution of ṁB2T, which starts increasing. T2stops following the target value T2Tgt, but it always remains below the maximum value T2... When T2

[0188]

[0189] reaches T2(instant t5), ṁB2Tbecomes lower than ṁB2Tand the flow rate ṁB2Tdetermined by feedforward control starts following ṁB2T. • This is the case of a passive battery heating and an active cabin heating, with CabRecoveryPred = 1. In the case of the absence of an active battery heating (thus, in conditions of passive heating), the temperature T2Tgtremains equal to the current temperature of the battery.

[0190] In the case of a combined heating, and with CabRecoverypred= 1, it is presumed that the flow rate ṁB2Tdetermined by feedforward control follows ṁB2T.However, when the current temperature of the heat transfer liquid at the inlet of the device BAT_HX approaches the target value T2Tgt, the flow rate ThB2Tsuffdecreases significantly. Moreover, if the one or more traction components rej ect more thermal power than the power currently used by the heat exchanger CA_HX, or than the power potentially stored to be destined thereto, the flow rate ṁB2Tdetermined by feedforward control can instead follow ṁB2T

[0191]

[0192] B2T.

[0193] Figure 9 comprises five diagrams 9A, 9B, 9C, 9D, 9E which are synchronized in time, and wherein:

[0194] the diagram 9A shows the evolution of the temperatures T2, T2Max, T2rgt,

[0195] the diagram 9B shows the evolution of the temperatures T3, TT2B,

[0196] the diagram 9C shows the evolution of the temperatures T4, T4,

[0197]

[0198] 4, T4.,

[0199] - the diagram 9D shows the evolution of the flow rates of the type ṁB2T, including ṁB2T, ṁB2T, ṁB2T,

[0200]

[0201] - the diagram 9E shows the evolution of the electric power PwrECH.

[0202] The results of the simulation which can be observed in the diagrams 9A-9E (combined cabin + battery heating, with CabRecoveryPred = 1) are similar to the behaviour observed in the scenario of battery heating only, with a remarkable exception:

[0203]

[0204] keeps on following the evolution of ṁB2T, whereas

[0205]

[0206] remains at zero, since T4never exceeds T4- As a consequence, without additional energy available, the second spill flow rate is regulated in such a way as to supply only the amount which is strictly necessary for the battery heating.

[0207] If CabRecoverypred= 0 holds true, the evolution of ṁB2Tfollows ṁB2T, since there is no convenience in storing energy in the prediction of a subsequent reuseof the heat rejected by the one or more traction components for heating the cabin before the end of the mission (the logical state of CabRecoverypredis by definition evidence of such a circumstance).

[0208] When the current temperature of the heat transfer liquid at the inlet of the device BAT_HX (temperature T2, instant t6) reaches the target value T2and the power PwrECHabsorbed by the heater ECHCabdecreases to the zero value – in the same way as ṁB2T– the flow rate ṁB2Tdetermined by feedforward control follows ṁB2T• As a consequence, the evolution of T2distinctly separates from T2and stays at T2.

[0209] Referring to Figures 10 to 12, there will now be described the preferred modes for determining the value

[0210]

[0211] ṁB2T. closed-loop control is based, in the same way as the feedforward control, on the temperatures of the heat transfer liquid. Specifically, referring to Figure 10, diagram 40, the error ERR as a function whereof a proportional-integral controller 41 operates is determined as the greater (block 42, MAX) of the following:

[0212] - a difference (block 43) between a sum (block 44 ) of the target value T2Tgtof the temperature of the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX with a temperature reserve ΔTPushof the third flow rate mBatof heat exchange liquid at the inlet of the battery heat exchange device BAT_HX and a current temperature value T2of the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX ( thus T2+ ΔTPush- T2)

[0213] and one of:

[0214] - the lesser (block 45, MIN) of a second difference (46) T4— T4Minbetween the temperature T4of the first flow rate mTrcof heat transfer liquid at the exit of the atleast one traction component TRC, and the minimum permissible value T4Minof the temperature of the first flow rate mTrcof heat transfer liquid at the outlet of the at least one traction component TRC, and a third difference T2Max— T2between the maximum admissible value T2Max°f the temperature T2of the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX and the value T2of the temperature of the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX if there is (CabRecoverypred= 1, control variable C40 for a switch SW40, route " T") an indication of the possibility of requesting the first spill flow rate ṁT2C,ṁC2Tby the cabin circuit L_CAB;

[0215] - the third difference (block 47 ) T2Max— T2if there is no (CabRecoverypred= 0, control variable C40 for the switch SW40, route " F") indication of the possibility of requesting the first spill flow rate ṁT2C,ṁC2Tby the cabin circuit L_CAB.

[0216] In other words, it is defined as a function of three temperature errors of the heat transfer liquid, specifically:

[0217] i) a first error El, corresponding to the difference T4— T4Min(vblock 46) ’, which is the error on the flow rate

[0218]

[0219] ii) a second error E2, corresponding to the difference T2Max— T2(block 47), which is the error on the flow rate mB2Tn

[0220] iii) a third error E3 corresponding to the difference (r2Tgt+ & TPushBa^ - T2resulting from the set of

[0221]

[0222] the blocks 34, 44, and which corresponds to the error on the flow rate mB2T. ΔTPushis - in the same way as

[0223]

[0224] TPushCab- a calibration amount required for exploiting as much as possible the thermal heating power coming from the second spill flow rate.Always referring to the determination of the error ERR, if the temperature T2is lower than the value T2Max, or if the temperature T2is lower than the target value T2Tincreased by the amount TPushBat, the second spill flow rate towards the battery circuit L_BAT may increase. As a consequence, the coefficients Kpand

[0225]

[0226] of the controller PI must always be positive or equal to zero for each value of the error signal.

[0227] Referring to the Figures 11 and 12, in order to keep the value ṁB2TCLwithin predefined limits, there are defined a lower saturation limit PILowerSaturationLimitand an upper saturation limit PIupperSaturationLimit for the controller PI. The lower saturation limit is schematically shown in Figure 11, diagram 50, and it corresponds to the opposite (block 52, sign reversal) of the value IB2TFFdetermined by feedforward control. In other words, the correction in closed loop must not be higher than the value calculated by feedforward control, so as to avoid negative values of the second spill flow rate.

[0228] The upper saturation limit PIUpperSaturationLimitFigure 12, diagram 60, is equal to a difference (block 62 ) between the lower (block 64 ) of the target value of the third flow rate of heat transfer liquid ṁBatTgt, the maximum value of the second spill flow rate ṁB2TMax, the maximum value of the first flow rate of heat transfer liquid ṁTrcMax, and the value of the second spill flow rate ṁB2TFFdetermined by means of feedforward control. In other words, the upper saturation limit corresponds to the margin available for the closed-loop control with respect to the feedforward control (ṁB2TFF) / superiorly limited by the lowest of the flow rates ṁBatTgt, ṁB2TMaxand ṁTrcMax.

[0229] Thanks to the method according to the invention it is therefore possible to achieve an improved batteryperformance (including the useful life thereof ): this translates into an improved driving range in the long term and into a more reliable battery. Moreover, the method according to the invention leads to the achievement of an improved general efficiency, since it is possible to minimize the consumption of electric energy across the electric heaters (whichever thereof is present) by taking the best advantage possible of the thermal power which is available ( free) in the system. Substantially, it is possible to maximize the exploitation of the thermal power rejected by the one or more traction components, by keeping the availability thereof even when its use is no longer needed, while meeting the targets and limitations related to the thermal conditioning, specifically to the heating, of the cabin and of the battery of the electric powertrain.

[0230] Of course, the implementation details and the embodiments may amply vary with respect to what has been described and illustrated herein, without departing from the extent of the present invention, as defined by the annexed claims.

Claims

CLAIMS1. A method for determining a spill flow rate value (mT2B,mB2T) in a thermal conditioning circuit (TCC) with heat transfer liquid of a vehicle with an electric powertrain, wherein the thermal conditioning circuit (TCC) includes a traction circuit (L_TRC), a cabin circuit (L_CAB), and a battery circuit (L_BAT), the cabin circuit being connected in fluid communication with the traction circuit by means of a first delivery branch and a first return branch configured for the transit of a first spill flow rate (ṁT2C,ṁC2T) coming from and returning to the traction circuit, the battery circuit being connectable in fluid communication with the traction circuit by means of a second delivery branch and a second return branch configured for the transit of a second spill flow rate (mT2B,mB2T) coming from and returning to the traction circuit,wherein the traction circuit (L_TRC) includes:- at least one traction component (TRC) of said powertrain traversed by a first flow rate of heat transfer liquid (ṁTrc) in a first flow direction (Fl ), said at least one traction component (TRC) comprising an electric traction motor (Ml, M2, M3, M4 ), an inverter ( INV1, INV2, INV3, INV4 ) operatively associated with the electric traction motor and a heat exchanger for a transmission lubricant (WTOC1_WTOC2, WTOC3. WTOC4 ) of a transmission connecting each electric traction motor to one or more corresponding drive wheels of the vehicle, a first circulation pump (P_TRC1 ) having a delivery port upstream of said at least one traction component (TRC) with respect to the first flow direction (Fl ) of said heat transfer liquid, the first circulation pump (TP) supplying said first flow rate mTrc) to the at least one traction component (TRC),where the cabin circuit (L_CAB) includes:- a cabin heat exchange device (CAB_HX) configured to operate in a heat exchange relationship with a cabin air flow and traversed by a second flow rate ('rhcab ') of heat transfer liquid in a second flow direction (F2 ), an electric cabin heater (ECHca ) arranged upstream of the cabin heat exchange device (CAB_HX) with respect to the second flow direction (F2 ) and traversed by the second flow rate ('r cab ') of heat transfer liquid in the second flow direction (F2 ),where the battery circuit (L_BAT) includes:a battery heat exchange device (BAT_HX) configured to operate in a heat exchange relationship with a battery for the power supply of one or more electric traction motors of the powertrain, the battery heat exchange device (BAT_HX) being traversed by a third flow rate mBat) of heat transfer liquid in a third flow direction ( F3 ),the method including determining a target value ṁB2TTgt) of the second spill flow rate (mT2B, mB2T) as a combination of a first value of the second spill flow rate (ṁB2TFF) determined by feedforward control, and a second value of the second spill flow rate (mB2TCL) determined by closed-loop control, wherein determining the first value of the second spill flow rate (ṁB2TFF) by feedforward control includes:- determining a sufficient value (ṁB2TSuff) of said second spill flow rate (mB2T) as a function of a target value (ṁBatTgt) of the third flow rate (ṁBatTgt) of heat transfer liquid, as a function of a temperature (T3) ofthe third flow rate of heat transfer liquid at the outlet of the battery heat exchange device (BAT_HX), as a function of a target value T2Tgtof a temperature (T2) of the third flow rate ('rhBat) of heat transfer liquid at an inlet of the battery heat exchange device (BAT_HX), and as a function of a temperature (TT2Bi) of the firstflow rate (ṁTrc) of heat transfer liquid at an inlet of the second delivery branch,- determining a maximum value of the second spill flow rate (mB27’Ma%)as afunction of a target value (Jiisatr 1 QZ of the third flow rate (?^Bat) °f the heat transfer liquid, as a function of a temperature (T3) of the third flow rate at the outlet of the battery heat exchange device (BAT_HX), as a function of a maximum permissible value of a temperature of the third flow rate (?^Bat) °f heat transfer liquid at an inlet of the battery heat exchange device (BAT_HX), and as a function of the temperature (T^B; ) of the first flow rate (m ) of the heat transfer liquid at the inlet of the second delivery branch,- determine a reserve value (ṁB2TExtHt) of the second flow rate (ṁB2T) as a function of a maximum permissible value (ṁTrcMax) of the first flow rate (ṁTrc) of the heat transfer liquid, as a function of the temperature (T3) of the third flow rateof the heat transfer liquid at the outlet of the battery heat exchange device (BAT_HX), as a function of a minimum permissible value (T7Min) he temperature of the first flow rate (mTrc) of heat transfer liquid at an inlet of at least one traction component (TRC), and as a function of the temperature (TT2Bi) of the first flow rate (mTrc) of heat transfer liquid at the inlet of the second discharge branch, where the minimum permissible value (T7n,. ) of the temperature of the first flow rate (ṁTrc) of heat transfer liquid at an inlet of at least one tensile component (TRC) is a function of a minimum permissible value (T4Minof the temperature of the first flow rate (mTrc) of heat transfer liquid at an outlet of at least one tensile component (TRC), and where the minimum permissible value (74Min) of the temperature of the first flow rate (ṁTrc) of heat transfer liquid at the outletof at least one traction component (TRC) is a function of a target value(T1Tgt+ ΔTPushCab) of the temperature of the second flow rate (ṁCab) of heat transfer liquid at the inlet of the cabin heat exchange device (CAB_HX), - determining the first value of the second spill flow (mB2T) in raw form (riiB2Tcc) as the greater (22 ) of ‘‘‘‘Rawthe sufficient value of the second spill flow rate (ṁB2TSuff) and the lower (24 ) of the said reserve value of the second spill flow rate(ṁB2TExtHtand the maximum value of the second spill flow rate'i if there is (SW20, CabRecoverypred= 1) an indication of the possibility of requesting the first spill flow rate (mT2C, mC2T) by the cabin circuit (L_CAB), or as the greater (22 ) between the sufficient value of the second spill flow rate (mB27’Suyy) and the maximum value of the second spill flow rate ṁB2TMax) if there is no indication (SW20, CabRecoverypred= 0) of the possibility of requesting the first spill flow rate ( mT2C, mC2T) by the cabin circuit (L_CAB),- calculating the value of the second flow rate (ṁB2TFF) determined by feedforward control as the greater (32 ) of a zero value (34 ) and the lower (36) of the target value of the third flow rate ṁBatTgt) of heat transfer liquid, the maximum value of the first flow rate ṁTrcMaxof heat transfer liquid, and the first value of the second spill flow rate (ṁB2T) in raw form (™B2TFFRaW}’- calculating the second value of the second spill flow rate (mB2TCL) determined by means of a closed-loop control as a function of an error (ERR) depending at least on the temperature (T4) of the first flow rate (mTrc) of heat transfer liquid at the outlet of at least one traction component (TRC), on the minimum admissible value (T4Minof the temperature of the first flow rate (mTrc) of heat transfer liquid at the outlet of the atleast one traction component (TRC), the temperature (T2) of the third flow rate (ṁBat) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX), the maximum permissible value ( T2Max) of the temperature of the third flow rate ( ṁBat) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX), and the target value (T2Tgt) of the temperature of the third flow rate ( ṁBat) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX).

2. The method of claim 1, wherein determining the target value (ṁB2TTgt) of the second spill flow rate (mT2B, mB2T) as a combination of a first value of the second spill flow rate (ṁB2TFF) determined by means of a feedforward control, and a second value of the second spill flow rate ( ṁB2TCL) determined by means of a closed- loop control includes determining the greater (2 ) of a zero value (4 ) and the lower ( 6) of:- a sum ( 8 ) of the first value of the second spill flow rate ṁB2TFF) determined by means of a feedforward control, and of the second value of the second spill flow rate (ṁB2TCL) determined by means of a closed-loop control,- the target value (ṁBatTgt) of the third flow rate of heat transfer liquid,- a maximum value ṁTrcMax) of the first flow rate of heat transfer liquid,the maximum value of the second spill flow rate(ṁB2TMax).

3. The method of any of the foregoing claims, wherein said error (ERR) is determined to be the greater (42 ) of:- a first difference (43) between a sum (44 ) of the target value ( T2Tgt) of the temperature of the third flow rate (ṁBat) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX) with a temperaturereserve ( TPush) of the third flow rate (riiBat 'l of heat transfer liquid at one inlet of the battery heat exchange device (BAT_HX) and a current value (T2) of the temperature of the third flow rate (ṁBat) of heat transfer liquid at the inlet of the battery heat exchange device of (BAT_HX),and one of:the lesser (45) of a second difference (46) between the temperature (T4) of the first flow rate (mTrc) of heat transfer liquid at the outlet of at least one traction component (TRC) and the minimum permissible value (T4Minof the temperature of the first flow rate (mTrc) of heat transfer liquid at the outlet of at least one traction component (TRC), and a third difference (47 ) between the maximum permissible value (T2.. ) of the temperature (T2) of the third flow rate (ṁBatTgt) of heat transfer liquid at the inlet of the exchange device (BAT_HX) and the value (T2) of the temperature of the third flow rate (ṁBat) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX) if there is (SW40, CabRecoverypred= 1) an indication of the possibility of requesting the first spill flow rate (mT2C, mC2T) by the cabin circuit (L_CAB).- the third difference (47 ) between the maximum permissible value (T2Max) of the temperature ( T2) of the third flow rate (ṁBatTgt) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX) and the value (T2) of the temperature of the third flow rate (ṁBat) of heat transfer liquid at the inlet of the coil heat exchange device (BAT_HX) if there is no (SW40, CabRecoverypred= 0 ) an indication of the possibility of requesting the first flow rate (mT2C, mC2T) by the cabin circuit (L_CAB).

4. The method according to any of the foregoing claims, where the second value of the second spill flowrate (mB2TCL) determined by a closed-loop control is calculated by means of a proportional-integral controller (41 ) operating on the basis of said error (ERR) and having a lower saturation limit equal to the opposite of that value of the second spill flow rate (ṁB2TFF) determined by means of a feedforward control, and an upper saturation limit equal to a difference ( 62 ) between the lower of said target values of the third flow rate of heat transfer liquid (ṁBatTgt), the maximum value of the first flow rate of heat transfer liquid (?iiTrc.. ), the maximum value of the second spill flow rate (mB2T.. ) and the value of the second spill flow rate (ṁB2TFF) determined by means of a feedforward control.

5. The method under any of the foregoing claims, in which the cabin circuit (L_CAB) further includes:a second circulation pump (P_CAB) having a delivery port upstream of said electric cabin heater (ECHcab) with respect to the second flow direction (F2 ) of said heat transfer liquid, the second circulation pump (CP) supplying said second flow (ṁCab) to the electric cabin heater (ECHcab) and to the cabin heat exchange device (CAB_HX).

6. The method of any of the foregoing claims, wherein the at least one traction component (TRC) in the traction circuit (L_TRC) includes, for each electric traction motor, at least one hydraulic series between the inverter ( INV1, INV2, INV3, INV4 ) operatively associated with the electric traction motor (Ml, M2, M3, M4 ), the electric traction motor itself (Ml, M2, M3, M4 ), and the heat exchanger for a transmission lubricant (WTOC1, WTOC2, WTOC3, WTOC4 ) of a transmission that connects the electric traction motor (Ml, M2, M3, M4 ) to one or more corresponding drive wheels.

7. The method of claim 6, including a plurality of hydraulic series connected in parallel with each other.

8. The method of any of the foregoing claims, wherein the minimum permissible value (T4) of the temperature of the first flow rate (ṁTrc) of heat transfer liquid at the outlet of at least one traction component (TRC) is determined as the sum of the targetvalue of the temperature of the second flow rate (ṁCab) °f heat transfer liquid at the inlet of the cabin heat exchange device (CAB_HX) and a temperature reserve (^TPushcab) of the second flow rate (ṁCab) of heat transfer liquid at the inlet to the cabin heat exchange device (CAB_HX).

9. The method of any of the foregoing claims, wherein the traction circuit (L_TRC) comprises a radiator (RAD) configured for cooling the heat transfer liquid leaving the one or more traction components (TRC), the radiator (RAD) being arranged downstream of the one or more traction components in the first flow direction (Fl ), the radiator (RAD) further being arranged parallel to the traction circuit along a circuit branch extending from an inlet node (VT2R) to an outlet node (R2T) the inlet node (V2TR) and the outlet node (R2T) being arranged between a connection circuit node (T2C / 1 ) of the first delivery branch on the traction circuit (L_TRC) and a connection circuit node (C2T) of the first return branch on the traction circuit,where said temperature (TT2Bi) of the first flow rate (ṁTrc) °f heat transfer liquid at an inlet of the second return branch is estimated by means of a virtual temperature sensor (ST2B) according to the relation:ṁC2T· T6+ (ṁTrc- ṁC2T) · TR2Twherein:TT2BI is the temperature (TT2Bi) of the first flow rate (ṁTrc) °f heat transfer liquid at an inlet of the second return branch,ṁC2Tisatarget value of the first spill flow rate ṁTrcis a target value of the first flow rate of heat transfer liquidT6is a current temperature of the heat transfer liquid upstream of a connection circuit node of the first return branch on the cabin circuit (L_CAB)TR2Tis a temperature of the heat transfer liquid at a position between the outlet node (R2T) of the radiator (RAD) and the connection circuit node (C2T) of the first return branch on the traction circuit (L_TRC),10. The method of claim 9, wherein the temperature of the heat transfer liquid at the position between the outlet node (R2T) of the radiator (RAD) and the connection circuit node (C2T) of the first return branch on the traction circuit (L_TRC) is estimated by means of an additional virtual temperature sensor (SR2T) according to the relation:ṁT2R· T5+ (ṁTrc- ṁC2T- ṁT2R) · T4TR2T= (ṁTrc- ṁC2T) wherein:TR2Tis said temperature of the heat transfer liquid at the position between the outlet node (R2T) of the radiator (RAD) and the connection circuit node (C2T) of the first return branch on the traction circuit (L_TRC), T5is a current temperature of the heat transfer liquid leaving the radiator (RAD) of the one or more traction components (TRC),T4is a current temperature of the heat transfer liquid leaving the one or more traction components.

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